The invention relates to a top-hat furnace system for annealing metal coils, having an annealing understructure, which is seated on a furnace foundation and on which at least one metal coil can be placed with its coiling axis vertical, and having an annealing hood, which can be placed in a sealing manner on the annealing understructure and over which a heating hood or alternatively a cooling hood can be placed.
To anneal metal coils, use is made of xe2x80x9ctop-hatxe2x80x9d annealing furnaces. These are manufactured by various firms, Junker, Ebner and LOI inter alia. The prior art described below can be found in brochures published by the above firms, e.g. the Ebner Journal, Volume 2, (September 1998). A system made by Junker is known from 1978, this system likewise being described in a company advertising publication.
The term metal coils in this context should be taken to mean bundles or rings of strips, wires and tubes. In this context, the metal coils are arranged on an annealing understructure in such a way that their coiling axis is vertical. A plurality of coils is generally stacked one above the other, being separated from one another by an intermediate layer, a so-called convector plate or convector star. An annealing hood connected in a sealing manner to the annealing understructure is then placed over the coil or coils, allowing the interior of the annealing hood to be supplied with a protective gas. To heat the annealing hood including the annealing stock, i.e. the metal coils, a heating hood fitted with appropriate heating devices is placed over the annealing hood.
Once annealing has been completed, the heating hood is removed again and replaced by a cooling hood, which ensures accelerated cooling of the annealing hood and of the annealing stock in it.
Placement of the metal coils on the annealing understructure and placement of the hoods is performed by means of a crane system.
For handling with conventional transportation means, e.g. fork-lift trucks, the metal coils are mounted in such a way that their coiling axis is horizontal. This makes it possible, for example, to insert the lifting arms of a fork-lift truck into the coil and thus raise and transport the latter easily. If appropriate, they may also be removed from a rolling stand and conveyed directly to the top-hat furnace system by the crane using a so-called C hook. To place a coil in a top-hat furnace, it must therefore be turned by 90xc2x0 out of its transportation position. For this purpose, use is made of a so-called tilting cradle. The tilting cradle has an arbor or a similar guide element onto which the metal coil is first of all placed, if appropriate after a convector plate has been placed on top. The tilting cradle is mounted so as to be tiltable at one side and, after a metal coil has been placed on it, it is tilted by 90xc2x0, with the result that the coiling axis of the coil now occupies a vertical position.
The coil is then clasped and raised with special tongs or the convector plate on which the coil may then already be resting is raised by means of crane hooks and chains, which simultaneously support the coil laterally, and the coil is moved to the annealing understructure of the top-hat furnace and placed on this understructure. The convector plates must have the necessary strength for this purpose, i.e. they must be dimensioned to be raised with a coil. For the top-hat furnace, they thus represent a quantity of xe2x80x9cdeadxe2x80x9d material which has to be heated with the rest.
The annealing hood, the heating hood and the cooling hood are provided with corresponding lifting lugs, allowing them likewise to be raised and transferred by means of the crane. Guide means connected to the annealing understructure are furthermore required during placement to ensure the exact position of the coils and the hoods.
The handling of the coils and the hoods as described requires considerable investment for the top-hat furnace system. For work with a crane, for instance, the shop must have a corresponding height or the annealing understructure must be arranged in correspondingly deep foundation pits. Despite the helpful guide means, precise placement of the coils and hoods and their removal on completion of annealing require experienced and continuously alert operating personnel and are indeed not without risk.
The object on which the invention is based is to specify a top-hat furnace system which requires less investment and which makes it possible to operate more quickly, more economically and with less risk.
According to the invention, the object is achieved by virtue of the fact that at least one arbor extending normal to the base surface of the annealing understructure is mounted on said annealing understructure, the annealing understructure, including the annealing hood and the metal coil or coils, is mounted in such a way as to be tiltable by 90xc2x0 between a vertical and a horizontal position, the annealing hood can be placed on the annealing understructure and removed from the latter in its horizontal position, both the heating hood and the cooling hood are provided laterally with opening and closing means, giving rise to an opening which allows through the annealing hood, and both the heating hood and the cooling hood can be moved in a vertical position horizontally relative to the annealing hood.
It is preferable if the pivot about which the annealing understructure can be tilted is located horizontally in an imaginary plane passing vertically through the base surface of the annealing understructure. The closer the tilting point is moved toward the center of gravity of the annealing understructure, the shorter is the tilting lever and hence the force that has to be applied to tilt the annealing understructure. Tilting can be performed with conventional hydraulic systems.
It is expedient if the heating hood and the cooling hood are provided with a door to open one side. The door can be of single-or double-wing design and be mounted on hinges on the hoods. It can also be configured as a flap that can be raised. It is possible, for example, for the hoods to be movable on rails.
It is now possible to dispense with an expensive crane system or deep foundation pits for loading and unloading the top-hat furnace and for transporting the hoods. The metal coils are placed on the guide means of the annealing understructure, which is tilted up by 90xc2x0, in their customary transportation position, i.e. with their coiling axis horizontal. If appropriate, they are conveyed to the annealing understructure directly from a rolling stand on a C hook of a simple traveling trolley. For this purpose, the arbors on the annealing understructure are slotted in the axial direction, allowing the C hook to run into these slots in order to deposit the coils. By virtue of the configuration of the top-hat furnace system in accordance with the invention, it is even possible to automate this process.
If the intention is to place a plurality of coils one above the other in the furnace, a convector plate is placed between each pair of coils during loading but this convector plate must now only be dimensioned in such a way that it can withstand the pressure of the coil or coils above it. After loading the coils, the annealing hood is placed on the annealing understructure in a horizontal position over the coils and connected to said understructure. For this purpose, a transportation vehicle based on the principle of a fork-lift truck or, once again, the traveling trolley can be provided, for example. The annealing understructure, including the annealing hood and the metal coils accommodated therein, is then tilted back by 90xc2x0 into the vertical position.
It is in this position that annealing is performed. For this purpose, the opened heating hood is first of all moved over the annealing hood in a vertical position and then closed. After annealing, the heating hood is replaced by a cooling hood of similar construction. Since a number of furnace systems are generally accommodated in one shop, the operating cycle can be chosen so that one furnace system is being loaded or unloaded while another one is annealing and a third is in the cooling mode.
Times for loading and unloading the top-hat furnaces and changing the hoods can be reduced considerably compared with the previous method.
There is also no longer any need to handle the metal coils with tongs, which always presented a risk of surface damage to the annealing stock.
Finally, safety for workers is improved throughout the entire handling process.
The invention will be explained in greater detail with reference to an exemplary embodiment.
In the associated drawings,